Lifting mechanism with interlock and method

ABSTRACT

The disclosure relates to a lifting mechanism for opening and closing a tool of a packaging machine. The lifting mechanism comprises at least one first lifting device and at least one second lifting device which can be actuated in succession in order to move the lifting mechanism from an open position to a closed position, wherein the first lifting device is decoupled from a load absorption caused by means of the second lifting device for closing the tool. The lifting mechanism comprises at least one adjustable locking mechanism for force-related decoupling of the first lifting device from a force flow caused by the second lifting device. Furthermore, the disclosure relates to a corresponding method.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) to German patent application number DE 10 2022 107 346.7, filed Mar. 29, 2022, which is incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a lifting mechanism for opening and closing a tool of a packaging machine. The disclosure further relates to a method for opening and closing a tool of a packaging machine.

BACKGROUND

Lifting mechanisms are conventionally used on intermittently operating packaging machines, for example deep-drawing packaging machines, in order to open and close work stations, for example a forming station, a sealing station and/or a cutting station, in cycles in order to carry out processing operations on supplied packaging materials.

DE 42 16 207 C1 discloses a packaging machine with a cutting device that can be opened and closed by means of a piston-cylinder device. In order to better absorb the forces occurring during the cutting process, the piston-cylinder device can be decoupled from the cutting process by means of a wedge which can be retracted into its piston. The cutting forces built up during the cutting process thus do not act on the piston stroke.

However, when lifting heavy tool assemblies, the known piston-cylinder decoupling reaches its limits.

SUMMARY

A problem of the disclosure is to provide a lifting mechanism which can be used in particular for lifting heavy tool assemblies and, in particular, for generating large lifting forces. A further problem of the disclosure is to provide a corresponding method.

The disclosure relates to a lifting mechanism for opening and closing a tool of a packaging machine, wherein the lifting mechanism comprises at least one first lifting device and at least one second lifting device, which can be actuated in succession in order to move the lifting mechanism from an open position to a closed position, wherein the first lifting device is decoupled from a load absorption caused by means of the second lifting device for closing the tool. According to the disclosure, the lifting mechanism has at least one adjustable locking mechanism for the force-related decoupling of the first lifting device from a force flow caused by the second lifting device. This locking mechanism makes it possible to block the first lifting device at least temporarily while a maximum closing force of the tool is built up by means of the second lifting device.

The locking mechanism used in the disclosure ensures that the first lifting device merely lifts the weight of a tool lower part and/or tool upper part formed thereon, so to speak as a displacement lifting device for closing the tool, however, for applying the power lift required for a work process, the second lifting device operates decoupled from the first lifting device as a power lifting device, i.e., the first lifting device remains unloaded by the use of the locking mechanism when carrying out the power lift. This enables gentle operation of the lifting mechanism, in particular the first lifting device, even when heavy tool components are to be moved by means of the lifting mechanism and/or high tool closing forces are required.

Preferably, the locking mechanism can be clamped by at least one component formed on the first lifting device in order to decouple the first lifting device from the force flow caused by the second lifting device. It is conceivable that the locking mechanism has at least one linearly or rotatably adjustable blocking element that can be coupled to or engaged with the first lifting device such that a force generated by the second lifting device can be shielded from the first lifting device.

One variant provides that the locking mechanism has an adjusting drive that can be controlled separately from the first and second lifting devices. Such an adjusting drive could, for example, be a pneumatically operated linear drive or a pneumatically operated pivoting drive.

According to one embodiment of the disclosure, the lifting mechanism has at least one base plate supported by a tie rod and adjustably mounted along the tie rod by means of the first lifting device. The tie rod, which can be used to support the base plate, can be attached to a machine frame of the packaging machine by means of a holder, for example by means of a bent holding plate or a rail.

It is conceivable that the base plate is configured to support a tool lower part, for example a sealing gland. This tool lower part could be configured as a tray receptacle for receiving a predetermined format of prefabricated packaging lower parts.

Preferably, the second lifting device is arranged between the base plate and the tool lower part, wherein the tool lower part can be lifted from the base plate by means of the second lifting device in order to build up the power lift, thus, a pretension between the tool lower part and a tool upper part positioned above it.

A construction that is easy to manufacture results from the fact that the lifting mechanism comprises at least one height-adjustable stop for stopping a lifting movement of a tool holder used to support the tool upper part. This allows the first lifting device to be relieved in particular of a weight of the tool upper part as soon as the tool holder provided for this purpose is seated on the stop. In particular, during a closing process of the lifting mechanism, at the time when the tool holder seats on the stop, an upper lifting movement of the tool upper part can stop and a load change can take place. This load change results in the fact that, from the time when the upper lifting movement of the tool upper part stops, the tool lower part, which is positioned on the base plate, is lifted, causing the tool to close as a whole. The tool parts can thus be lowered and lifted one after the other, wherein the weight forces caused by the tool parts each act individually on the first lifting device.

It would be conceivable that the stop is mounted in a height-adjustable manner, for example as a bolt with an external thread screwed to the machine frame. This enables the use of different tool parts.

Preferably, the first lifting device has at least one lifting cylinder with an extendable piston which can be controlled both for adjusting the tool upper part and for adjusting the tool lower part. It is conceivable that even several such lifting cylinders, for example four lifting cylinder modules, are provided on the circumferential side of the lifting mechanism.

According to a preferred embodiment of the disclosure, the second lifting device comprises at least one inflatable membrane for lifting the tool lower part. This inflatable membrane can be positioned between the tool lower part and the base plate positioned below it in order to lift the tool lower part on the base plate following the force-related decoupling of the first lifting device by the locking mechanism in order to carry out the power lift for a predetermined work process. Thereby, the base plate is fixed by the locking mechanism so that no force can be transmitted from it to the lifting cylinder(s).

The disclosure further relates to a packaging machine, in particular in the form of a deep-drawing packaging machine or in the form of a tray-sealing machine, wherein at least one lifting mechanism of the type described above is mounted thereon. For example, a corresponding lifting mechanism could be present at a forming station, a sealing station and/or a cutting station of the deep-drawing packaging machine in order to move the tools used thereon. Alternatively, the lifting mechanism can be used at a sealing station of the tray-sealing machine.

The disclosure further relates to a method for opening and closing a tool of a packaging machine by means of a lifting mechanism formed thereon. According to this method, a first lifting device and a second lifting device are actuated in succession to move the lifting mechanism from an open position to a closed position, wherein the first lifting device is decoupled from a load absorption caused by the second lifting device to close the tool. For this purpose, a locking mechanism is adjusted between a base plate of the lifting mechanism, which can be adjusted by means of the first lifting mechanism, and a cylinder plate of a lifting cylinder formed on the first lifting device. This allows the first lifting device to be blocked such that it is isolated from a subsequent lifting movement carried out by means of the second lifting device to generate a power lift, thus, not being loaded by forces built up by means of the power lift.

It is conceivable that the locking mechanism is clamped between the base plate and the cylinder plate for the force-related decoupling of the first lifting device from a force flow caused by the second lifting device. For example, a blocking element formed on the locking mechanism could be engaged with the first lifting device such that the base plate is thereby fixed relative to the cylinder plate. It would be conceivable that the blocking element is linearly adjusted or pivoted between the base plate and the cylinder plate.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is explained in more detail with reference to the following Figures.

FIG. 1 shows a schematic side view of a deep-drawing packaging machine;

FIG. 2 shows a perspective schematic diagram of a tray-sealing machine;

FIG. 3 shows a lifting mechanism according to the disclosure in its open position;

FIG. 4 shows the lifting mechanism from FIG. 3 with the tool upper part lowered;

FIG. 5 shows the lifting mechanism from FIG. 4 with the tool lower part lifted;

FIG. 6 shows the lifting mechanism from FIG. 5 with activated locking mechanism; and

FIG. 7 shows the lifting mechanism from FIG. 6 carrying out a power lift.

Identical components are identified throughout the Figures by the same reference signs.

DETAILED DESCRIPTION

FIG. 1 shows a packaging machine 100A configured as an intermittently operating deep-drawing packaging machine 20. This deep-drawing packaging machine 20 has a forming station 21, a sealing station 22, a transverse cutting device 23 and a longitudinal cutting device 24, which are arranged in this order in a production direction R on a machine frame 25. On the input side, a feed roller 26 is located on the machine frame 25, from which a lower film 27 is drawn off. Furthermore, the deep-drawing packaging machine 20 has a transport chain 28 which grips the lower film 27 and transports it further in production direction R per main working cycle.

In the embodiment shown, the forming station 21 is configured as a deep-drawing station in which troughs M are formed in the lower film 27 by deep drawing, for example by means of compressed air and/or vacuum. The forming station 21 can be configured such that several troughs M are formed next to one another in the direction perpendicular to the production direction R.

In the production direction R downstream of the forming station 21, a filling path or insertion area 29 is provided along which the packaging troughs M are filled with products. The packaging troughs M can be filled manually by an operator or mechanically by a picker.

The sealing station 22 has a hermetically sealable chamber 22 a in which the atmosphere in the packaging troughs M can be evacuated and/or replaced, for example, by gas purging with an exchange gas or with a gas mixture before sealing with an upper film 31 dispensed from a film holder 30.

The transverse cutting device 23 can be configured as a punch which cuts through the lower film 27 and the upper film 31 in a direction transverse to the production direction R between adjacent packaging troughs M. In this process, the transverse cutting device 23 operates in such a way that the lower film 27 is not cut across its entire width, but is at least not cut in an edge region. This enables controlled onward transport through the transport chain 28.

The longitudinal cutting device 24 can be configured as a knife arrangement with which the lower film 27 and the upper film 31 are cut between adjacent packaging troughs M and at the side edge of the lower film 27 in the production direction R, so that separated packages V are present downstream of the longitudinal cutting device 24.

The deep-drawing packaging machine also has a control device 32. This has the task of controlling and monitoring the processes running in the deep-drawing packaging machine 20. A display device 33 is used to visualize or influence the process sequences in the deep-drawing packaging machine 20 for or by an operator.

FIG. 2 shows another packaging machine 100B, which is a tray-sealing machine 40. Such a tray-sealing machine 40 is also called a tray sealer in specialist circles. The tray-sealing machine 40 has a feed conveyor 41 on which prefabricated tray parts 42 are transported. Furthermore, the tray-sealing machine 40 has a gripping device 43. By means of the gripping device 43, the tray parts 42 provided on the feed conveyor 41 can be picked up and transferred for a sealing process to a sealing station 44 of the tray-sealing machine 40. Tray parts 42 received therein are sealed with an upper film 45 fed through the sealing station 44. After the sealing process, the sealed tray parts 42 are picked up by the gripping device 43 and transferred to a discharge conveyor 46 of the tray-sealing machine 40.

FIG. 3 shows a lifting mechanism 100 and a tool 50 that can be adjusted with it in an open position 51. The lifting mechanism 100 has a base plate 1 which, in the open position 51, is supported on a machine frame, for example the machine frame 25 of FIG. 1 , by means of a tie rod 2 and a holding plate 3. On the base plate 1, a lifting plate 4, in which at least one membrane 5 is integrated, is mounted. A tool lower part 6 is located thereon, which is configured, for example, as a sealing gland.

A cylinder piston 7 a of a lifting cylinder 7 is attached to the base plate 1, which is in the retracted state in the open position 51 according to FIG. 3 . The lifting cylinder 7 lifts, by means of a cylinder plate 8 formed thereon and at least one tie rod 9 standing thereon, a tool holder 10 on which a tool upper part 11, for example a sealing tool upper part, is mounted.

In addition, a stop 12 and a locking mechanism 13 are shown in FIG. 3 . Their function will be described later in connection with FIGS. 4-7 .

In order to close the tool 50, the lifting cylinder 7 is first extended from the adjustment shown in FIG. 3 . This is shown in FIG. 4 . The lifting cylinder 7 is supported on the base plate 1. When the lifting cylinder 7 is extended, the cylinder plate 8 and the tie rod 9 are lowered in the direction F1, causing the tool holder 10 to come into contact with the stop 12. The stop 12 can be adjusted so that the tool upper part 11 stops when it seats flush on the upper film 31, 45.

At the time when the tool holder 10 seats on the stop 12, an upper lifting movement of the tool upper part 11 along the direction F1 stops and a load change takes place, i.e., a lower lifting movement of the tool lower part 6 starts. This is shown in FIG. 5 . The tie rod 2 is relieved of load and the stop 12 is loaded with the weight force of the entire lifting mechanism 100. Beyond the load change, the lifting cylinder 7 is extended in direction F2 until the base plate 1 together with the tool lower part 6 is in contact with the tool upper part 11.

In FIG. 5 , the tool upper part 11 and the tool lower part 6 are moved towards each other to the maximum extent by means of the lifting cylinder 7. In this position, the locking mechanism 13, in particular a blocking element 13 a formed thereon, is positioned between the base plate 1 and the cylinder plate 8 by means of a linear or pivoting movement. This is shown in FIG. 6 .

In order to build up pretension between the tool lower part 6 and the tool upper part 11, at least one membrane 5 contained in the lifting plate 4 is pressurized so that it clamps the base plate 1 onto the locking mechanism 13. In the process, the lifting plate 4 is supported by the base plate 1 in the direction F3, as a result of which the lifting mechanism 100 reaches a closed position S2 as shown in FIG. 6 in order to carry out a working process, for example a sealing process.

After the locking mechanism 13 has been clamped against the cylinder plate 8, the force flow takes place between the membrane 5, the lifting plate 4, the tool lower part 6, the tool upper part 11, the tool holder 10, the tie rods 9, the cylinder plate 8, the locking mechanism 13 and the base plate 1. The lifting cylinder 7 does not generate any part of the closing force of the lifting mechanism 100 that builds up in the process, remains decoupled from the power lift, so to speak. The weight force of the lifting mechanism 100 rests on the stop 12.

The lifting mechanism 100 offers the advantage that the power lift and the travel lift take place decoupled from each other. As a result, the lifting cylinders 7 only have to move the weight forces and the power lift only has to cover a very short distance, whereby optimum utilization of the membrane 5 can be achieved. It is thus possible to apply relatively low forces to the lifting cylinders 7, which means that they can be configured to be smaller and can therefore be controlled with low energy consumption. Overall, this results in a cost-effective configuration and operation of the lifting cylinders 7. 

What is claimed is:
 1. A lifting mechanism for opening and closing a tool of a packaging machine, wherein the lifting mechanism comprises a first lifting device and a second lifting device which can be actuated in succession in order to move the lifting mechanism from an open position to a closed position, wherein the first lifting device is decoupled from a load absorption caused by means of the second lifting device for closing the tool, wherein the lifting mechanism comprises an adjustable locking mechanism for force-related decoupling of the first lifting device from a force flow caused by the second lifting device.
 2. The lifting mechanism according to claim 1, wherein the locking mechanism for the force-related decoupling of the first lifting device from the force flow caused by the second lifting device can be clamped by at least one component formed on the first lifting device.
 3. The lifting mechanism according to claim 1, wherein the locking mechanism comprises an adjusting drive which can be controlled separately from the first and second lifting devices.
 4. The lifting mechanism according to claim 1, wherein the lifting mechanism comprises at least one base plate supported by a tie rod and adjustably mounted along the tie rod by means of the first lifting device.
 5. The lifting mechanism according to claim 1, wherein the lifting mechanism comprises at least one height-adjustable stop for stopping a lifting movement of a tool holder used to support a tool upper part.
 6. The lifting mechanism according to claim 5, wherein the first lifting device comprises at least one lifting cylinder with an extendable piston, which is controllable for closing the tool both for adjusting the tool upper part and for adjusting a tool lower part.
 7. The lifting mechanism according to claim 6, wherein the second lifting device comprises at least one inflatable membrane for lifting the tool lower part.
 8. A packaging machine formed as a deep-drawing packaging machine or a tray-sealing machine, comprising the lifting mechanism according to claim
 1. 9. A method for opening and closing a tool of a packaging machine by means of a lifting mechanism formed thereon, the method comprising: actuating a first lifting device and a second lifting device in succession for adjusting the lifting mechanism from an open position to a closed position, wherein the first lifting device is decoupled from a load absorption caused by means of the second lifting device for closing the tool; and adjusting a locking mechanism between a base plate of the lifting mechanism, which is adjustable by means of the first lifting device, and a cylinder plate formed on a lifting cylinder of the first lifting device.
 10. The method according to claim 9, wherein the locking mechanism is clamped between the base plate and the cylinder plate for force decoupling of the first lifting device from a force flow caused by the second lifting device. 